Video content distribution system and content management server

ABSTRACT

A video content distribution system including a user terminal and a content management server connected via a communication network. The content management server continues transmitting field-of-view video data associated with a first viewpoint to the user terminal at least for a time period from the time when a transmission unit transmits a viewpoint switch request signal for requesting a switch from the first viewpoint to a second viewpoint to the time when a reception unit receives field-of-view video data associated with the second viewpoint. In response to the reception unit receiving the viewpoint switch request signal, a viewing stop time determining unit determines a first viewing stop time at which viewing display stops displaying the field-of-view video from the first viewpoint, and a viewing start time determining unit determines a second viewing start time at which the display start displaying the field-of-view video from the second viewpoint.

RELATED APPLICATIONS

The present application claims priority to Japanese Application Number2015-252311, filed Dec. 24, 2015, the disclosure of which is herebyincorporated by reference herein in its entirety.

BACKGROUND

This disclosure relates to a video content distribution system and acontent management server that is provided in the video contentdistribution system.

Video content distribution systems are configured to distribute videocontents over the Internet or other communication. In Japanese PatentNo. 5,377,466, there is disclosed a video content distribution systemconfigured to distribute a plurality of video contents over acommunication network to the general public. Each user can view a videocontent of his/her choice by selecting a channel that is associated withthe video content out of a plurality of channels.

While the video content distribution system disclosed in Japanese PatentNo. 5,377,466 allows a user to view a video content that is selected bythe user out of a plurality of video contents, a video contentdistribution system that enables a user to view the same video contentfrom different viewpoints is not disclosed in Japanese Patent No.5,377,466.

SUMMARY

An object of at least one embodiment of this disclosure is to provide avideo content distribution system capable of improving a degree ofsatisfaction with a video content distribution service for a user whoviews the same video content from different viewpoints. An object of atleast one embodiment of this disclosure is to provide a contentmanagement server that is provided in the video content distributionsystem.

According to at least one embodiment of this disclosure, there isprovided a video content distribution system, including a user terminalon which contents are viewable and a content management server. The userterminal and the content management server are connected in a mannerthat allows communication to one another via a communication network.

The user terminal includes a first reception unit configured to receivefield-of-view video data from the content management server. The userterminal further includes a display control unit configured to displayon a display unit a field-of-view video based on the receivedfield-of-view video data. The user terminal further includes a viewpointswitch request signal generating unit configured to generate, inresponse to input operation performed by a user on the user terminal, aviewpoint switch request signal for requesting a switch from a firstviewpoint, which is a current viewpoint, to a second viewpoint in thefield-of-view video displayed on the display unit. The user terminalfurther includes a first transmission unit configured to transmit thegenerated viewpoint switch request signal to the content managementserver.

The content management server includes a second reception unitconfigured to receive the viewpoint switch request signal from the userterminal. The content management server further includes a viewing starttime determining unit configured to determine a first viewing start timeat which the user starts viewing the field-of-view video from the firstviewpoint, and a second viewing start time at which the user startsviewing the field-of-view video from the second viewpoint. The contentmanagement server further includes a viewing stop time determining unitconfigured to determine a first viewing stop time at which the userstops viewing the field-of-view video from the first viewpoint, and asecond viewing stop time at which the user stops viewing thefield-of-view video from the second viewpoint. The content managementserver further includes a viewing period determining unit configured todetermine a first viewing period in which the field-of-view video isviewed from the first viewpoint based on the first viewing start timeand the first viewing stop time, and to determine a second viewingperiod in which the field-of-view video is viewed from the secondviewpoint based on the second viewing start time and the second viewingstop time. The content management server further includes a secondtransmission unit configured to transmit to the user terminalfield-of-view video data that is associated with one of the firstviewpoint and the second viewpoint.

The content management server is configured to keep transmitting thefield-of-view video data that is associated with the first viewpoint atleast for a period from a time when the first transmission unittransmits the viewpoint switch request signal to the second transmissionunit to a time when the first reception unit receives the field-of-viewvideo data that is associated with the second viewpoint from the contentmanagement server, or at least for a period from a time when the secondreception unit receives the viewpoint switch request signal to a timewhen the second transmission unit transmits the field-of-view video datathat is associated with the second viewpoint.

The viewing stop time determining unit and the viewing start timedetermining unit are configured to determine the first viewing stop timeand the second viewing start time, respectively, when the secondreception unit receives the viewpoint switch request signal.

According to at least one embodiment of this disclosure, providing thevideo content distribution system capable of improving the degree ofsatisfaction with the video content distribution service for the userwho views the same video content from different viewpoints is possible.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a video content distribution systemaccording to some embodiments of this disclosure.

FIG. 2 is a diagram of at least one example of the hardwareconfiguration of a user terminal.

FIG. 3 is a diagram of function blocks of a control unit of the userterminal according to at least one embodiment of this disclosure.

FIG. 4 is a diagram of at least one example of the layout of audienceseats in a concert hall.

FIG. 5 is a diagram of at least one example of the hardwareconfigurations of a content management server and content servers.

FIG. 6 is a diagram of function blocks of a control unit of the contentmanagement server according to at least one embodiment.

FIG. 7 is a diagram of function blocks of a control unit of each contentserver according to at least one embodiment.

FIG. 8 is a sequence diagram of a series of processes of the videocontent distribution system according to at least one embodiment.

FIG. 9 is a table of at least one example of a user viewpointinformation management table.

FIG. 10 is a table of at least one example of a user viewpointinformation management table.

FIG. 11 is a table of at least one example of a content managementtable.

FIG. 12 is a diagram of function blocks of a control unit of the contentmanagement server according to at least one embodiment.

FIG. 13 is a sequence diagram of a series of processes of the videocontent distribution system according to at least one embodiment.

FIG. 14 is a diagram of function blocks of a control unit of the userterminal according to at least one embodiment of this disclosure.

FIG. 15 is a diagram of function blocks of a control unit of the contentmanagement server according to at least one embodiment.

FIG. 16 is a sequence diagram of a series of processes of the videocontent distribution system according to at least one embodiment.

DETAILED DESCRIPTION

(1) A video content distribution system includes a user terminal onwhich contents are viewable and a content management server. The userterminal and the content management server are connected in a mannerthat allows communication to one another via a communication network.The user terminal includes a first reception unit configured to receivefield-of-view video data from the content management server. The userterminal further includes a display control unit configured to displayon a display unit a field-of-view video based on the receivedfield-of-view video data. The user terminal further includes a viewpointswitch request signal generating unit configured to generate, inresponse to input operation performed by a user on the user terminal, aviewpoint switch request signal for requesting a switch from a firstviewpoint, which is a current viewpoint, to a second viewpoint in thefield-of-view video displayed on the display unit. The user terminalfurther includes a first transmission unit configured to transmit thegenerated viewpoint switch request signal to the content managementserver. The viewpoint switch request signal includes user ID informationidentifying the user and viewpoint information indicating the secondviewpoint. The content management server includes a second receptionunit configured to receive the viewpoint switch request signal from theuser terminal. The content management server includes a viewing starttime determining unit configured to determine a first viewing start timeat which the user starts viewing the field-of-view video from the firstviewpoint, and a second viewing start time at which the user startsviewing the field-of-view video from the second viewpoint. The contentmanagement server further includes a viewing stop time determining unitconfigured to determine a first viewing stop time at which the userstops viewing the field-of-view video from the first viewpoint, and asecond viewing stop time at which the user stops viewing thefield-of-view video from the second viewpoint. The content managementserver further includes a viewing period determining unit configured todetermine a first viewing period in which the field-of-view video isviewed from the first viewpoint based on the first viewing start timeand the first viewing stop time, and to determine a second viewingperiod in which the field-of-view video is viewed from the secondviewpoint based on the second viewing start time and the second viewingstop time. The content management server further includes a secondtransmission unit configured to transmit to the user terminalfield-of-view video data that is associated with one of the firstviewpoint and the second viewpoint. The content management server isconfigured to keep transmitting the field-of-view video data that isassociated with the first viewpoint at least for a period from a timewhen the first transmission unit transmits the viewpoint switch requestsignal to the second transmission unit to a time when the firstreception unit receives the field-of-view video data that is associatedwith the second viewpoint from the content management server, or atleast for a period from a time when the second reception unit receivesthe viewpoint switch request signal to a time when the secondtransmission unit transmits the field-of-view video data that isassociated with the second viewpoint. The viewing stop time determiningunit and the viewing start time determining unit are configured todetermine the first viewing stop time and the second viewing start time,respectively, when the second reception unit receives the viewpointswitch request signal.

According to at least one embodiment of the configuration describedabove, field-of-view video data that is associated with the firstviewpoint is continues being transmitted to the user terminal at leastfor a period from the time when the first transmission unit transmitsthe viewpoint switch request signal to the second reception unit to thetime when field-of-view video data that is associated with the secondviewpoint is received from the content management server, or at leastfor a period from the time when the second reception unit receives theviewpoint switch request signal to the time when the second transmissionunit transmits field-of-view video data that is associated with thesecond viewpoint.

In this manner, when a switch from the first viewpoint to the secondviewpoint is made in a field-of-view image provided to the userterminal, the field-of-view image of the first viewpoint is switchedseamlessly to the field-of-view image of the second view point, therebyallowing the user to enjoy viewing the field-of-view image fromdifferent viewpoints without being frustrated by a blank image or abuffering signal indicator.

A video content distribution system capable of improving the degree ofsatisfaction with a video content distribution service for a user whoviews the same video content from different viewpoints can thus beprovided.

In addition, the first viewing period during which a field-of-view imageis viewed from the first viewpoint is determined based on the firstviewing start time and the first viewing stop time, and the secondviewing period during which the field-of-view image is viewed from thesecond viewpoint is determined based on the second viewing start timeand the second viewing stop time. Determining the length of time inwhich a field-of-view image is viewed for each different viewpointseparately in this manner means that field-of-view video viewing perioddata can be recorded for each viewpoint and for each user. This viewingperiod data can be utilized to improve the user's degree of satisfactionwith a video content distribution service.

(2) A video content distribution system according to Item (1), in whichthe content management server further includes a user charge informationupdating unit configured to update user charge information that isassociated with the first viewpoint based on the first viewing period,and to update user charge information that is associated with the secondviewpoint based on the second viewing period.

According to at least one embodiment of the configuration describedabove, user charging information that is associated with the firstviewpoint is updated based on the first viewing period, and usercharging information that is associated with the second viewpoint isupdated based on the second viewing period. A metered-rate chargingsystem that is based on the field-of-view video viewing period of eachviewpoint can be provided in this manner, which helps to improve theuser's degree of satisfaction with a video content distribution serviceand to convince the user more that the charge for the service is fair.

(3) A video content distribution system according to Item (1) or (2), inwhich the content management server further includes a total user chargeamount calculating unit configured to determine a total amount to thecharged to the user for the viewing of the field-of-view video based onpieces of user charge information that are associated with therespective viewpoints.

According to at least one embodiment of the configuration describedabove, the total charge amount to be charged to the user for the viewingof a field-of-view video is determined based on pieces of user chargeinformation that are associated with respective viewpoints. Ametered-rate charging system that is based on the field-of-view videoviewing period of each viewpoint can be provided in this manner, whichhelps to improve the user's degree of satisfaction with a video contentdistribution service and to convince the user more that the charge forthe service is fair.

(4) A video content distribution system according to any one of Items(1) to (3),

in which the content management server further includes a transmissionstart time determining unit configured to determine a transmission starttime at which the second transmission unit starts transmitting thefield-of-view video data that is associated with the second viewpoint tothe user terminal. The viewing stop time determining unit is configuredto determine as the first viewing stop time an acquisition time at whichthe viewpoint switch request signal is obtained. The viewing start timedetermining unit is configured to determine as the second viewing starttime the transmission start time that is determined by the transmissionstart time determining unit.

According to at least one embodiment of the configuration describedabove, an acquisition time at which the viewing stop time determiningunit obtains user ID information is determined as the first viewing stoptime, and a transmission start time at which the second transmissionunit starts transmitting field-of-view video data that is associatedwith the second viewpoint to the user terminal is determined as thesecond viewing start time. A period between the acquisition time and thetransmission start time is not counted as a field-of-view video viewingperiod in this manner, which helps to improve the user's degree ofsatisfaction with a video content distribution service and to convincethe user more that the charge for the service is fair.

(5) A video content distribution system according to any one of Items(1) to (3),

in which the content management server further includes a transmissionstart time determining unit configured to determine a transmission starttime at which the second transmission unit starts transmitting thefield-of-view video data that is associated with the second viewpoint tothe user terminal. The content management server further includes acommunication delay predicting unit configured to predict a delay incommunication between the content management server and the userterminal. The content management server further includes an arrival timepredicting unit configured to predict an arrival time at which thefield-of-view video data that is associated with the second viewpointarrives at the user terminal, based on the determined transmission starttime and the predicted communication delay. The viewing stop timedetermining unit is configured to determine as the first viewing stoptime an acquisition time at which the viewpoint switch request signal isobtained. The viewing start time determining unit is configured todetermine as the second viewing start time the arrival time that ispredicted by the arrival time predicting unit.

According to at least one embodiment of the configuration describedabove, an acquisition time at which the viewing stop time determiningunit obtains user ID information is determined as the first viewing stoptime, and an arrival time at which the field-of-view video data that isassociated with the second viewpoint arrives at the user terminal isdetermined as the second viewing start time. A period between theacquisition time and the arrival time is not counted as a field-of-viewvideo viewing period in this manner, which helps to improve the user'sdegree of satisfaction with a video content distribution service and toconvince the user more that the charge for the service is fair.

(6) A video content distribution system according to any one of Items(1) to (3),

in which the user terminal further includes a time stamp generating unitconfigured to generate a first time stamp and a second time stamp. Thefirst time stamp indicates a transmission start time at which the firsttransmission unit starts transmitting the viewpoint switch requestsignal to the content management server. The second time stamp indicatesa display start time at which the display control unit starts displayingon the display unit the field-of-view video from the second viewpoint.The second reception unit is configured to receive the first time stampand the second time stamp from the user terminal. The viewing stop timedetermining unit is configured to determine as the first viewing stoptime the transmission start time that is indicated by the received firsttime stamp. The viewing start time determining unit is configured todetermine as the second viewing start time the display start time thatis indicated by the received second time stamp.

According to at least one embodiment of the configuration describedabove, a transmission start time indicated by the first time stamp whichis when the first transmission unit starts transmitting the viewpointswitch request signal to the content management server is determined asthe first viewing stop time, and a display start time indicated by thesecond time stamp which is when the display control unit startsdisplaying the field-of-view image from the second viewpoint on thedisplay unit is determined as the second viewing start time. A periodbetween the transmission start time and the display start time is notcounted as a field-of-view video viewing period in this manner, whichhelps to improve the user's degree of satisfaction with a video contentdistribution service and to convince the user more that the charge forthe service is fair.

(7) A content management server, which is connected to a user terminalon which contents are viewable in a manner that allows communicationbetween the user terminal and the content management server via acommunication network. The content management server includes a secondreception unit configured to receive a viewpoint switch request signalfrom the user terminal. The content management server further includes aviewing start time determining unit configured to determine a firstviewing start time at which a user starts viewing a field-of-view videofrom a first viewpoint, and a second viewing start time at which theuser starts viewing the field-of-view video from a second viewpoint. Thecontent management server further includes a viewing stop timedetermining unit configured to determine a first viewing stop time atwhich the user stops viewing the field-of-view video from the firstviewpoint, and a second viewing stop time at which the user stopsviewing the field-of-view video from the second viewpoint. The contentmanagement server further includes a viewing period determining unitconfigured to determine a first viewing period in which thefield-of-view video is viewed from the first viewpoint based on thefirst viewing start time and the first viewing stop time, and todetermine a second viewing period in which the field-of-view video isviewed from the second viewpoint based on the second viewing start timeand the second viewing stop time. The content management server furtherincludes a second transmission unit configured to transmit to the userterminal field-of-view video data that is associated with one of thefirst viewpoint and the second viewpoint. The field-of-view video datathat is associated with the first viewpoint is kept transmitted to theuser terminal at least for a period from a time when the secondreception unit receives the viewpoint switch request signal to a timewhen the second transmission unit transmits the field-of-view video datathat is associated with the second viewpoint. The viewing stop timedetermining unit and the viewing start time determining unit areconfigured to determine the first viewing stop time and the secondviewing start time, respectively, when the second reception unitreceives the viewpoint switch request signal.

According to at least one embodiment of the configuration describedabove, field-of-view video data that is associated with the firstviewpoint is kept transmitted to the user terminal at least for a periodfrom the time when the second reception unit receives the viewpointswitch request signal to the time when the second transmission unittransmits field-of-view video data that is associated with the secondviewpoint.

In this manner, when a switch from the first viewpoint to the secondviewpoint is made in a field-of-view image provided to the userterminal, the field-of-view image of the first viewpoint is switchedseamlessly to the field-of-view image of the second view point, therebyallowing the user to enjoy viewing the field-of-view image fromdifferent viewpoints without being frustrated by a blank image or abuffering signal indicator.

A content management server capable of improving the degree ofsatisfaction with a video content distribution service for a user whoviews the same video content from different viewpoints can thus beprovided.

In addition, the first viewing period during which a field-of-view imageis viewed from the first viewpoint is determined based on the firstviewing start time and the first viewing stop time, and the secondviewing period during which the field-of-view image is viewed from thesecond viewpoint is determined based on the second viewing start timeand the second viewing stop time. Determining the length of time inwhich a field-of-view image is viewed for each different viewpointseparately in this manner means that field-of-view video viewing perioddata can be recorded for each viewpoint and for each user. This viewingperiod data can be utilized to improve the user's degree of satisfactionwith a video content distribution service.

Embodiments of this disclosure are described below with reference to thedrawings. Once a component is described in this description ofembodiments, a description on a component having the same referencenumber as that of the already described component is omitted for thesake of convenience.

FIG. 1 is a block diagram of a video content distribution system 100according to some embodiments of this disclosure. As illustrated in FIG.1, the video content distribution system 100 includes a plurality ofuser terminals 2X and 2Y, on which video contents can be viewed, acontent management server 3, and a plurality of content servers 5S, 5A,5B, 5C, and 5D. The user terminals 2X and 2Y, the content managementserver 3, and the content servers 5S, 5A, 5B, 5C, and 5D are connectedvia a communication network 1, which is a local area network (LAN), awide area network (WAN), the Internet, or the like, in a manner thatallows communication to one another. In the following description, theuser terminals 2X and 2Y are simply referred to as “user terminals 2”,the content servers 5S, 5A, 5B, 5C, and 5D are simply referred to as“contents servers 5” for the sake of convenience.

The hardware configuration of the user terminals 2 is described nextwith reference to FIG. 2. As illustrated in FIG. 2, each user terminal 2includes a control device 21, an input operation unit 28, a display unit27, and a sensor 29. The control device 21 includes a communication bus20, a control unit 22, a storage 23, an input/output (I/O) interface 24,a time clock 25, and a communication interface 26. The control unit 22,the storage 23, the I/O interface 24, the time clock 25, and thecommunication interface 26 are connected by the communication bus 20 ina manner that allows communication to one another. The control device 21is, for example, a personal computer, a smartphone, a tablet, or awearable device.

The control unit 22 includes a memory and a processor. The memory isbuilt from, for example, a read only memory (ROM) on which variousprograms are able to be stored, or a random access memory (RAM) that hasa plurality of work areas where various programs executed by theprocessor and data are able to be stored. The RAM includes a VRAM onwhich video data associated with a video that is displayed on thedisplay unit 27 is able to be stored. The processor is built from atleast one of a central processing unit (CPU), a micro-processing unit(MPU), a graphic processing unit (GPU), or another processing unituniquely configured to the tasks of control unit 22.

The storage 23 is configured to store various programs and video dataamong others, and is built from, for example, a hard disk drive (HDD), asolid state drive (SSD), a flash memory, or the like. The I/O interface24 is configured to connect the input operation unit 28, the displayunit 27, and the sensor 29 to the control device 21 in a manner thatallows communication to and from the control device 21. The I/Ointerface 24 is built from, for example, a universal serial bus (USB)terminal or a High-Definition Multimedia Interface (HDMI®).

The time clock 25 is configured to count the current time and is, forexample, a real time clock (RTC). The time clock 25 may synchronize withthe time of a device in the network (for example, the content managementserver) by using the Network Time Protocol (NPT). The communicationinterface 26 is configured to connect the user terminal 2 to thecommunication network 1.

The input operation unit 28 is configured to receive input operationfrom a user of the user terminal 2, and to output an operation signalthat indicates the user's input operation in response to the user'sinput operation. The input operation unit 28 is, for example, a touchpanel, an external controller, a mouse, or a keyboard. The display unit27 is configured to display a field-of-view video associated withfield-of-view video data, and is, for example, a head-mounted display(HMD) on which a three-dimensional image is provided to the user. TheHMD displays a left-eye image provided to the left eye of the user and aright-eye image provided to the right eye of the user, thereby providinga three-dimensional image that utilizes the parallax between the leftand right eyes to the user as a virtual reality (VR) image. The displayunit 27 may instead be the display, such as a display of a personalcomputer, a smartphone, or a tablet.

The sensor 29 is configured to detect the movement of the user wearingthe HMD by detecting the HMD's movement in XYZ directions and rotationabout XYZ axes. A change in sight line due to the movement of the user'shead is detected in this manner. The sensor 29 may be built from atleast one of a geomagnetic sensor, an acceleration sensor, or agyro-sensor that are provided in the HMD, or from an external camerathat detects a plurality of light emission points provided in the HMD.

Function blocks including the control unit 22 of the user terminal 2 aredescribed next with reference to FIG. 3. FIG. 3 is a diagram of functionblocks of the user terminal 2, including the control unit 22. Asillustrated in FIG. 3, the control unit 22 includes a reception unit221, e.g., a first reception unit, a display control unit 223, a sightline change signal generating unit 222, a viewpoint switch requestsignal generating unit 224, and a transmission unit 225, e.g., a firsttransmission unit.

The reception unit 221 is configured to receive field-of-view video datafrom the content management server 3 via the communication interface 26.The reception unit 221 may receive field-of-view video data in, forexample, a streaming format. The reception unit 221 may receive360-degree space video data that includes field-of-view video data fromthe content management server 3. In this case, the control unit 22 maygenerate field-of-view video data from the received 360-degree spacevideo data and from sight line information, which is about the directionof the user's line of sight. The display control unit 223 is configuredto generate instructions for displaying a field-of-view video on thedisplay unit 27 based on the received field-of-view video data. In atleast one embodiment, a field-of-view video is a virtual reality (VR)video that is displayed within the user's field of view out of a360-degree space video centered about the user's viewpoint. In otherwords, a field-of-view video is a part of a 360-degree space videocentered about the user's viewpoint, and is defined by the user's fieldof view. The user's field of view is defined by the direction of theuser's line of sight. In at least one embodiment, when the direction ofthe user's line of sight is determined, the user's field of view isdetermined and a field-of-view video is determined. Similarly, a changein the direction of the user's line of sight causes a change in theuser's field of view, which changes the field-of-view video. Types offield-of-view videos include, for example, concert videos, videos ofsports such as soccer, baseball, sumo, and combat sports, and videos oftheatrical art such as kabuki, Noh, and musicals.

The sight line change signal generating unit 222 is configured togenerate a sight line change signal based on a signal that is output bythe sensor 29 to indicate a change in the direction of the user's lineof sight. The sight line change signal contains sight line informationthat is about the changed sight line direction.

The viewpoint switch request signal generating unit 224 is configured togenerate a viewpoint switch request signal for requesting a switch fromthe current viewpoint to the next viewpoint in a field-of-view videothat is being displayed on the display unit 27 as instructed by inputoperation received from the user on the user terminal 2. In at least oneembodiment, the viewpoint switch request signal generating unit 224generates sight line information that indicates the line of sight afterthe switch based on an operation signal, which is output from the inputoperation unit 28 and which indicates the user's input operation, andreads user ID information of the user who is using the user terminal 2and address information of the user terminal 2 out of the storage 23. Aviewpoint switch request signal thus contains sight line information,user ID information, and address information of the user terminal 2.Viewpoints in a field-of-view video correspond to, for example,viewpoints from an S-seat area, an A-seat area, a B-seat area, a C-seatarea, or a D-seat area in a concert hall as illustrated in FIG. 4. Aviewpoint in the S-seat area is a viewpoint from a stage on whichartists perform. For instance, the viewpoint switch request signalgenerating unit 224 generates a viewpoint switch request signal forrequesting a switch from an A-seat area viewpoint, which is the currentviewpoint, to an S-seat area viewpoint, which is the next viewpoint, ina field-of-view video displayed on the display unit 27. User IDinformation of a user is, for example, a member ID that the user entersto use a video content distribution service. Address information of theuser terminal 2 is, for example, the IP address of the user terminal 2.The viewpoint switch request signal generating unit 224 may alsogenerate a viewpoint switch request signal for requesting a switch fromone viewpoint in a seat area, e.g. the S-seat area, to another point inthe same seat area, e.g. the same S-seat area, in a field-of-view videodisplayed on the display unit 27.

The transmission unit 225 is configured to transmit, to the contentmanagement server 3, via the communication interface 26, a viewpointswitch request signal generated by the viewpoint switch request signalgenerating unit 224 and a sight line change signal generated by thesight line change signal generating unit 225. In at least one embodimentwhere the user terminal 2 receives 360-degree space video data from thecontent management server 3, the sight line change signal is nottransmitted to the content management server 3.

The hardware configuration of the content management server 3 and thehardware configuration of the content servers 5 are described next withreference to FIG. 5. FIG. 5 is a diagram of at least one example of thehardware configurations of the content management server 3 and thecontent servers 5. As illustrated in FIG. 5, the content managementserver 3 includes a communication bus 30, a control unit 32, a storage33, a time clock 35, and a communication interface 36. The control unit32, the storage 33, the time clock 35, and the communication interface36 are connected via the communication bus 30 in a manner that allowscommunication to one another. The control unit 32 includes a memory anda processor. The memory is built from, for example, a ROM or a RAM. Theprocessor is built from, for example, at least one of a CPU, an MPU, aGPU or another processing unit uniquely configured to the tasks ofcontrol unit 32.

The storage 33 is configured to store various programs and video dataamong others, and is built from, for example, HDD, SSD, a flash memory,or the like. The time clock 35 has the same configuration as that of thealready described time clock 25, and may synchronize with the time ofthe user terminal and others by using the NTP. The communicationinterface 36 is configured to connect the content management server 3 tothe communication network 1.

The content server 5 includes a communication bus 50, a control unit 52,a storage 53, and a communication interface 56. The control unit 52, thestorage 53, and the communication interface 56 are connected via thecommunication bus 50 in a manner that allows communication to oneanother. The control unit 52 includes a memory and a processor. Thememory is built from, for example, a ROM and a RAM. The processor isbuilt from, for example, at least one of a CPU, an MPU, a GPU or anotherprocessing unit uniquely configured to the tasks of control unit 52.

The storage 53 is built from, for example, a large-capacity HDD, and isconfigured to store 360-degree space video data associated withviewpoints. For example, the storage 53 of the content server 5S isconfigured to store 360-degree space video data that is associated witha viewpoint in the S-seat area. The storage 53 of the content server 5Ais configured to store 360-degree space video data that is associatedwith a viewpoint in the A-seat area. The storage 53 of the contentserver 5B is configured to store 360-degree space video data that isassociated with a viewpoint in the B-seat area. The storage 53 of thecontent server 5C is configured to store 360-degree space video datathat is associated with a viewpoint in the C-seat area. The storage 53of the content server 5D is configured to store 360-degree space videodata that is associated with a viewpoint in the D-seat area. The360-degree space video data of each seat area may be picked up by a360-degree camera set up in the concert hall. For example, a 360-degreespace video is taken by a 360-degree camera that is set up in the S-seatarea (the stage on which artists perform). The 360-degree space videodata picked up by the 360-degree camera is then stored in the storage 53of the content server 5S. In at least one embodiment, where the videocontent distribution system 100 is intended for a user who views thesame video content from different viewpoints, pieces of 360-degree spacevideo data stored on the respective content servers 5S, 5A, 5B, 5C, and5D are of the same video content (for example, the same concert video).

While pieces of 360-degree space video data associated with differentviewpoints are stored separately on the plurality of content servers 5(5S, 5A, 5B, 5C, and 5D) in at least one embodiment, one content server5 may store pieces of 360-degree space video data of a plurality ofviewpoints. The communication interface 56 of each content server 5 isconfigured to connect the content server 5 to the communication network1.

Function blocks of the control unit 32 of the content management server3 according to at least one embodiment are described next with referenceto FIG. 6. FIG. 6 is a diagram of function blocks of the control unit 32of the content management server 3 according to at least one embodimentof this disclosure. As illustrated in FIG. 6, the control unit 32includes a reception unit 321, e.g. a second reception unit, aninformation obtaining unit 322, a viewing stop time determining unit326, a viewing start time determining unit 327, a viewing perioddetermining unit 328, a transmission start time determining unit 329, auser charge information management table updating unit 331, e.g. a usercharge information updating unit, a total user charge amount calculatingunit 330, a user viewpoint information management table updating unit324, a field-of-view video data request signal generating unit 323, anda transmission unit 325, e.g. a second transmission unit.

The reception unit 321 is configured to receive a viewpoint switchrequest signal and a sight line change signal from the user terminal 2via the communication interface 36. The reception unit 321 is alsoconfigured to receive field-of-view video data from the content servers5 via the communication interface 36. The information obtaining unit 322is configured to obtain user ID information, user viewpoint information,and address information of the user terminal 2 from the viewpoint switchrequest signal received by the reception unit 321. The informationobtaining unit 322 is also configured to obtain sight line informationabout a changed sight line direction, based on the sight line changesignal received by the reception unit 321.

The viewing stop time determining unit 326 is configured to determine aviewing stop time at which the user stops viewing a field-of-view videofrom the current viewpoint (for example, a viewpoint in the A-seatarea). The viewing start time determining unit 327 is configured todetermine a viewing start time at which the user starts viewing thefield-of-view video from the current viewpoint (for example, a viewpointin the A-seat area). The viewing period determining unit 328 isconfigured to determine the length of time in which the field-of-viewvideo is viewed from the current viewpoint (for example, a viewpoint inthe A-seat area), based on the viewing start time determined by theviewing start time determining unit 327 and the viewing stop timedetermined by the viewing stop time determining unit 326.

The transmission start time determining unit 329 is configured todetermine a transmission start time at which the transmission unit 325starts transmitting to the user terminal 2 field-of-view video data thatis associated with a post-switch viewpoint (for example, a viewpoint inthe S-seat area). The user charge information management table updatingunit 331 is configured to update data in a user charge informationmanagement table (see FIG. 10), which is stored in the storage 33. Inparticular, the user charge information management table updating unit331 is configured to update the accumulated viewing period (an exampleof user charge information) of viewing from the current viewpoint basedon how long the field-of-view video has been viewed from the currentviewpoint which is determined by the viewing period determining unit328.

The total user charge amount calculating unit 330 is configured todetermine the total amount to be charged to the user for the viewing ofa field-of-view video, based on accumulated viewing periods, e.g. atleast one example of user charge information, that are associated withthe respective viewpoints shown in FIG. 10, e.g. the S-seat area to theD-seat area.

As shown in FIG. 10, the user charge information management tableincludes, for each user, pieces of information about per-unit time feesassociated with the respective viewpoints, e.g. seat areas, pieces ofinformation about accumulated viewing periods associated with therespective viewpoints, charge amounts associated with the respectiveviewpoints, and the total amount to be charged to the user for theviewing of a field-of-view video. In at least one embodiment, each useris identified based on a user ID. In at least one example of the usercharge information management table of FIG. 10, an amount charged forthe viewing of a field-of-view video from a view point in the S-seatarea is calculated as 333 yen by 1,000 yen/time×20 minutes/60 minutes.For each user ID, the total amount to be charged to the user ID iscalculated by adding up charge amounts that are associated with therespective viewpoints. In at least one example of FIG. 10, the totalcharge amount is calculated as 667 yen by 333 yen (S seat)+133 yen (Aseat)+58 yen (B seat)+42 yen (C seat)+100 yen (D seat).

The user viewpoint information management table updating unit 324 isconfigured to update data in a user viewpoint information managementtable (see FIG. 9), which is stored in the storage 33. In particular,the user viewpoint information management table updating unit 324 adds,for each user, a viewpoint associated with the user (for example, theS-seat area) and a transmission start time of the viewpoint (forexample, 00:03) to the user viewpoint information management table,based on a transmission start time that is determined by thetransmission start time determining unit 329 and on the user's viewpointinformation obtained by the information obtaining unit 322. In the casewhere the user's viewpoint switches from a viewpoint in the A-seat areato a viewpoint in the S-seat area, for example, the viewpoint in theS-seat area and the transmission start time of the viewpoint are newlywritten in the user viewpoint information management table.

The field-of-view video data request signal generating unit 323 isconfigured to generate a field-of-view video data request signal forrequesting field-of-view video data. In particular, the field-of-viewvideo data request signal generating unit 323 is configured to read apost-switch viewpoint by referring to the user viewpoint informationmanagement table (see FIG. 9), which is stored in the storage 33. Thefield-of-view video data request signal generating unit 323 maycalculate a play start time at which the field-of-view video, based onthe field-of-view video data, is played from the post-switch viewpoint,based on, for example, information that is written in the user viewpointinformation management table. The field-of-view video data requestsignal generating unit 323 may also obtain address information (forexample, an IP address) of the content server 5 that is associated withthe post-switch viewpoint from a content management table (see FIG. 11),which is stored in the storage 33. A field-of-view video data requestsignal may thus contain address information of the post-switch viewpointand information about a play start time at which the field-of-view videois played from the post-switch viewpoint. The field-of-view videorequest signal may further contain sight line information about thechanged sight line direction which is obtained by the informationobtaining unit 322. The field-of-view video data request signal maycontain sight line information about the initial sight line direction(for example, a direction toward the center of the stage) instead ofsight line information about the changed sight line direction.

The transmission unit 325 is configured to transmit a field-of-viewvideo data request signal generated by the field-of-view video datarequest signal generating unit 323 to a desired content server 5 via thecommunication interface 36 and the communication network 1. Inparticular, the transmission unit 325 may transmit the field-of-viewvideo data request signal by referring to address information of thepost-switch viewpoint that is contained in the field-of-view video datarequest signal. The transmission unit 325 may transmit field-of-viewvideo obtained from the content server 5 to the user terminal 2. Thetransmission unit 325 may also transmit 360-degree space video dataobtained from the content server 5 that includes field-of-view videodata to the user terminal 2. In at least one embodiment, the userterminal 2 generates field-of-view video data from the 360-degree spacevideo data.

Function blocks of the control unit 52 of each content server 5 aredescribed next with reference to FIG. 7. FIG. 7 is a diagram of functionblocks of the control unit 52 of each content server 5. As illustratedin FIG. 7, the control unit 52 includes a reception unit 521, afield-of-view video data generating unit 522, and a transmission unit523. The reception unit 521 is configured to receive a field-of-viewvideo data request signal transmitted from the content management server3. The field-of-view video data generating unit 522 is configured togenerate, after reading 360-degree space video data out of the storage53, field-of-view video data based on the read 360-degree space videodata and on the received field-of-view video data request signal. In thecase of the content server 5S, for example, the field-of-view video datagenerating unit 522 reads 360-degree space video data that is associatedwith a viewpoint in the S-seat area out of the storage 53, and thengenerates field-of-view video data that is associated with the viewpointin the S-seat area based on the read 360-degree space video data and onthe received field-of-view video data request.

The transmission unit 523 is configured to transmit the field-of-viewvideo data generated by the field-of-view video data generating unit 522to the content management server 3 via the communication interface 56.The transmission unit 523 may transmit 360-degree space video data thatincludes field-of-view video data to the content management server 3. Inat least one embodiment, the 360-degree space video data is transmittedfrom the content management server 3 to the user terminal 2, wherefield-of-view video data is generated from the 360-degree space videodata.

A series of processes of the video content distribution system 100according to at least one embodiment is described next with reference toFIG. 8. FIG. 8 is a sequence diagram of a series of processes of thevideo content distribution system 100 according to at least oneembodiment. The description given here focuses on exchanges ofinformation between the user terminal 2X, which is used by a user X, andthe content management server 3 as illustrated in FIG. 8, to therebydescribe a charging method of the video content distribution system 100.One of ordinary skill in the art would understand that in at least oneembodiment exchanges of information between the user terminal 2Y, whichis used by a user Y, and the content management server 3 are similar tothe exchanges of information between the user terminal 2X and thecontent management server 3.

In Step S1, the user X performs, through the input operation unit 28,given operation for switching from a viewpoint in the A-seat area (afirst viewpoint), which is a pre-switch viewpoint, to a viewpoint in theS-seat area (a second viewpoint), which is a post-switch viewpoint. Inother words, the input operation unit 28 transmits to the viewpointswitch request signal generating unit 224 an operation signal thatindicates a request for a switch from the viewpoint in the A-seat areato the viewpoint in the S-seat area. As requested by the operationsignal transmitted from the input operation unit 28, the viewpointswitch request signal generating unit 224 generates a viewpoint switchrequest signal for requesting a switch from the viewpoint in the A-seatarea to the viewpoint in the S-seat area in a field-of-view video thatis being displayed on the display unit 27. In at least one embodiment,the viewpoint switch request signal generating unit 224 generatesviewpoint information that indicates the viewpoint in the S-seat areabased on the operation signal transmitted from the input operation unit28, and reads user ID information of the user X and address informationof the user terminal 2X out of the storage 23. The viewpoint switchrequest signal thus contains the viewpoint information that indicatesthe viewpoint in the S-seat area, the user ID information of the user X,and the IP address information of the user terminal 2X.

Next, the transmission unit 225 transmits the generated viewpoint switchrequest signal to the content management server 3 via the communicationinterface 26. The time at which the user terminal 2X transmits theviewpoint switch request signal is t0=00:01 as illustrated in FIG. 8.

In Step S2, the viewing stop time determining unit 326 refers to thecurrent time on the time clock 35 and information obtained by theinformation obtaining unit 322, to thereby determine an A-seat viewingstop time (a first viewing stop time) at which the user X stops viewingthe field-of-view video from the viewpoint in the A-seat area (the firstviewpoint). In at least one embodiment, the viewing stop timedetermining unit 326 determines as the A-seat viewing stop time a timeat which the viewpoint switch request signal (information contained inthe viewpoint switch request signal, to be exact) is obtained. Theviewing stop time is t1=00:02 as illustrated in FIG. 8.

Prior to Step S1, the viewing start time determining unit 327 hasdetermined an A-seat viewing start time (a first viewing start time) atwhich the user X starts viewing the field-of-view video from theviewpoint in the A-seat area (the first viewpoint). In at least oneembodiment, the viewing stop time determining unit 236 does not need tooperate (in other words, does not need to determine the A-seat viewingstop time) in the case where a viewpoint switch request signal receivedby the reception unit 321 is a request for a switch from one viewpointin the A-seat area to another viewpoint in the A-seat area (i.e., whenthe received viewpoint switch request signal is a request for a switchbetween viewpoints in the same seat area). In such cases, where theviewpoint is switched within the same seat area, the viewpoint starttime determining unit 327 does not need to operate either.

In this manner, when the viewpoint switch request signal received by thereception unit 321 is a request for a switch from the first viewpointthat belongs to a given seat area to the second viewpoint that belongsto a seat area different from the given seat area in a field-of-viewvideo displayed on the display unit 27 (or when the viewpoint switchrequest signal transmitted from the transmission unit 225 is thisrequest), the viewing stop time determining unit 326 determines thefirst viewing stop time at which the viewing of the field-of-view videofrom the first viewpoint is stopped and the viewing start timedetermining unit 327 determines a second viewing start time at which theviewing of the field-of-view video from the second viewpoint is started.

Next, the transmission start time determining unit 329 determines inStep S3 a transmission start time at which the transmission unit 325starts transmitting field-of-view video data that is associated with theviewpoint in the S-seat area to the user terminal 2X, by referring tothe current time on the time clock 35 and information obtained by theinformation obtaining unit 322. The transmission start time is t2=00:03.

In Step S4, the user viewpoint information management table updatingunit 324 updates data in the user viewpoint information management table(see FIG. 9), which is stored in the storage 33. In particular, the userviewpoint information management table updating unit 324 writes in theuser viewpoint information management table the transmission start timet2=00:03 determined by the transmission start time determining unit 329,the user ID information of the user X that is obtained by theinformation obtaining unit 322, and the viewpoint information indicatingthe viewpoint in the S-seat area that is obtained by the informationobtaining unit 322.

In Step S5, the content management server 3 obtains field-of-view videodata that is associated with the viewpoint in the S-seat area from thecontent server 5S, where 360-degree space video data that is associatedwith the viewpoint in the S-seat area is stored. In at least oneembodiment, the field-of-view video data request signal generating unit323 generates a field-of-view video data request signal for requestingfield-of-view video data. In at least one embodiment, the field-of-viewvideo data request signal generating unit 323 reads the viewpoint in theS-seat area by referring to the user viewpoint information managementtable (see FIG. 9), which is stored in the storage 33. The field-of-viewvideo data request signal generating unit 323 further calculates a playstart time at which the field-of-view video is played from the viewpointin the S-seat area, based on information that is written in the userviewpoint information management table, and obtains address informationof the content server 5S from the content management table (see FIG.11), which is stored in the storage 33. The field-of-view video datarequest signal may thus contain the address information of the contentserver 5S and information about the play start time at which thefield-of-view video is played from the viewpoint in the S-seat area. Thefield-of-view video data request signal may contain sight lineinformation about the initial sight line direction (for example, adirection toward the center of the stage) when the viewpoint of thefield-of-view video is switched.

Next, the transmission unit 325 refers to the address information of thecontent server 5S, to thereby transmit the field-of-view video datarequest signal generated by the field-of-view video data request signalgenerating unit 323 to the content server 5S via the communicationinterface 36 and the communication network 1. The content server 5Sreceives the field-of-view video data request signal, and then generatesfield-of-view video data that is associated with the viewpoint in theS-seat area based on the field-of-view video data request signal. Thecontent server 5S transmits the generated field-of-view video data tothe content management server 3. In at least one embodiment, thereception unit 521 of the content server 5S receives the field-of-viewvideo data request signal, and the field-of-view video data generatingunit 522 then reads 360-degree space video data that is associated withthe viewpoint in the S-seat area out of the storage 53. Thefield-of-view video data generating unit 522 generates field-of-viewvideo data that is associated with the viewpoint in the S-seat areabased on the read 360-degree space video data and on the receivedfield-of-view video data request signal. The transmission unit 523transmits the generated field-of-view video data to the contentmanagement server 3 via the communication interface 56. The contentmanagement server 3 receives 360-degree space video data that isassociated with the viewpoint in the S-seat area from the content server5S in this manner.

Next, the content management server 3 transmits in Step S6 thefield-of-view video data that is associated with the viewpoint in theS-seat area to the user terminal 2X. Specifically, the transmission unit325 refers to the transmission start time stored in the user viewpointinformation management table (t2=00:03) and the address information ofthe user terminal 2X that is obtained by the information obtaining unit322, to thereby transmit the field-of-view video data that is associatedwith the viewpoint in the S-seat area and that is stored in the storage33 to the user terminal 2X in a streaming format. The content managementserver 3, which transmits the field-of-view video data to the userterminal 2X in at least one embodiment, may instead transmit to the userterminal 2X the 360-degree space video data that includes thefield-of-view video data.

During a period from the time when the transmission unit 225 of the userterminal 2X transmits the viewpoint switch request signal to thereception unit 321 of the content management server 3 (t0=00:01) to thetime when the reception unit 221 of the user terminal 2X receives thefield-of-view video data that is associated with the viewpoint in theS-seat area (the second viewpoint) from the content management server 3,the content management server 3 (the transmission unit 325) keepstransmitting field-of-view video data that is stored in the storage 33as data associated with the viewpoint in the A-seat area (the firstviewpoint), which is the pre-switch viewpoint, to the user terminal 2Xin a streaming format. Alternatively, in at least one embodiment, thecontent management server 3 (the transmission unit 325) keepstransmitting field-of-view video data that is stored in the storage 33as data associated with the viewpoint in the A-seat area (the firstviewpoint), which is the pre-switch viewpoint, to the user terminal 2Xin a streaming format during a period from the time when the receptionunit 321 of the content management server 3 receives the viewpointswitch request signal from the user terminal 2X to the time when thetransmission unit 325 of the content management server 3 transmits thefield-of-view video data that is associated with the viewpoint in theS-seat area (the second viewpoint) to the user terminal 2X.

This allows the user X to keep viewing the field-of-view video from theviewpoint in the A-seat area during the period described above, as shownin Step S7. After a given length of time elapses (t3=00:04) since thetime when the user terminal 2X receives the field-of-view video datathat is associated with the viewpoint in the S-seat area, the displaycontrol unit 223 displays a field-of-view video from the viewpoint inthe S-seat area on the display unit 27 based on the field-of-view videodata that is associated with the viewpoint in the S-seat area (Step S8).This allows the user X to view the field-of-view video that isassociated with the viewpoint in the S-seat area from t3=00:04 on.

In this manner, when viewpoint switching operation for switching from aviewpoint in the A-seat area (the first viewpoint) to a viewpoint in theS-seat area (the second viewpoint) is performed on a field-of-view videoprovided to the user terminal 2X, the field-of-view video from theviewpoint in the A-seat area is switched seamlessly to the field-of-viewvideo from the viewpoint in the S-seat area, thereby allowing the user Xto enjoy viewing the field-of-view image from different viewpointswithout being frustrated by a blank image or a buffering icon. The videocontent distribution system 100 and the content management server 3 thatare provided in this embodiment are thus capable of improving the degreeof satisfaction with a video content distribution service for a user whoviews the same video content from different viewpoints.

Next, the viewing start time determining unit 327 determines in Step S9an S-seat viewing start time (the second viewing start time) at whichthe user X starts viewing the field-of-view video from the viewpoint inthe S-seat area, i.e., the post-switch viewpoint. In at least oneembodiment, the viewing start time determining unit 327 determines asthe S-seat viewing start time the transmission start time determined bythe transmission start time determining unit 329 (t2=00:03). Forexample, when the content management server 3 (the reception unit 321)receives after this step a viewpoint switch request signal that requestsa switch of the viewpoint of the field-of-view video from the viewpointin the S-seat area to a viewpoint in the B-seat area, the viewing stoptime determining unit 326 determines an S-seat viewing stop time (thesecond viewing stop time) at which the user X stops viewing thefield-of-view video from the viewpoint in the S-seat area (the secondviewpoint). In at least one embodiment, the viewing stop timedetermining unit 326 determines as the S-seat viewing stop time anacquisition time at which the viewpoint switch request signal isobtained.

When the content management server 3 (the reception unit 321) receivesthe viewpoint switch request signal, the viewing stop time determiningunit 326 determines the A-seat viewing stop time and the viewing starttime determining unit 237 determines the S-seat viewing start time asalready described.

The viewing period determining unit 328 determines an A-seat viewingperiod (a first viewing period) in which the field-of-view video isviewed from the viewpoint in the A-seat area, based on the A-seatviewing start time (the first viewing start time) and the A-seat viewingstop time (the first viewing stop time). Specifically, the viewingperiod determining unit 328 calculates the A-seat viewing period fromthe difference between the A-seat viewing stop time and the A-seatviewing start time (A-seat viewing stop time−A-seat viewing start time).

Similarly, the viewing period determining unit 328 determines an S-seatviewing period (a second viewing period) in which the field-of-viewvideo is viewed from the viewpoint in the S-seat area, based on theS-seat viewing start time (the second viewing start time) and the S-seatviewing stop time (the second viewing stop time). In at least oneembodiment, the viewing period determining unit 328 calculates theS-seat viewing period from the difference between the S-seat viewingstop time and the S-seat viewing start time (S-seat viewing stoptime−S-seat viewing start time).

According to at least one embodiment, the A-seat viewing period isdetermined based on the A-seat viewing start time and the A-seat viewingstop time and the S-seat viewing period is determined based on theS-seat viewing start time and the S-seat viewing stop time in thismanner. The length of time in which a field-of-view video is viewed isdetermined for each viewpoint separately, and thus field-of-view videoviewing period data can be recorded for each viewpoint and for eachuser, and the viewing period data can be used to improve the user'sdegree of satisfaction with a video content distribution service.

In addition, the user charge information management table updating unit331 updates the accumulated viewing period (user charge information)that is associated with the viewpoint in the A-seat area based on theA-seat viewing period, and updates the accumulated viewing period (usercharge information) that is associated with the viewpoint in the S-seatarea based on the S-seat viewing period (see FIG. 10). According to atleast one embodiment, a metered-rate charging system that is based onthe field-of-view video viewing period of each viewpoint can be providedin this manner, which helps to improve the user's degree of satisfactionwith a video content distribution service.

In addition, the total user charge amount calculating unit 330determines the total amount to be charged to the user X (667 yen in FIG.10) for the viewing of a field-of-view video based on accumulatedviewing periods (user charge information) that are associated with therespective viewpoints (the S-seat area to the D-seat area). Ametered-rate charging system that is based on the field-of-view videoviewing periods of the respective viewpoints (the S-seat area to theD-seat area) can be provided in this manner, which helps to improve theuser's degree of satisfaction with a video content distribution serviceand to convince the user more that the charge for the service is fair.

According to at least one embodiment, the viewing stop time determiningunit 326 determines as the A-seat viewing stop time an acquisition timeat which a viewpoint switch request signal (in particular, informationcontained in a viewpoint switch request signal, for example, user IDinformation) is obtained (t1=00:02), and a transmission start time atwhich the transmission unit 325 starts transmitting field-of-view videodata that is associated with the viewpoint in the S-seat area to theuser terminal 2X (t2=00:03) is determined as the S-seat viewing starttime. The period between the acquisition time t1 and the transmissionstart time t2 (1 second) is not counted as a field-of-view video viewingperiod in this manner, which helps to improve the user's degree ofsatisfaction with a video content distribution service and to convincethe user more that the charge for the service is fair.

The video content distribution system according to at least oneembodiment of this disclosure is described next with reference to FIG.12 and FIG. 13. FIG. 12 is a diagram of function blocks of a controlunit 32A of the content management server 3 according to at least oneembodiment. FIG. 13 is a sequence diagram of a series of processes ofthe video content distribution system according to at least oneembodiment. The video content distribution system, e.g., video contentdistribution system, according to at least one embodiment differs fromthe video content distribution system according to at least oneembodiment in the function of the control unit of the content managementserver 3. Specifically, the control unit 32A of the content managementserver 3 includes, in addition to the components of the control unit 32,a communication delay predicting unit 332 and an arrival time predictingunit 333.

As illustrated in FIG. 12, the communication delay predicting unit 332is configured to predict a delay in communication between the contentmanagement server 3 and each user terminal 2. A delay in communicationbetween the content management server 3 and the user terminal 2 is aperiod from the transmission of field-of-view video data that isassociated with the post-switch viewpoint by the transmission unit 325of the content management server 3 to the reception of thisfield-of-view video data by the reception unit 221 of the user terminal2. This means that the communication delay depends heavily on thecommunication environment of the communication network 1. For example,after the content management server 3 (the information obtaining unit322) obtains from the user terminal 2 information about the downstreamcommunication speed of field-of-view video data that is associated withthe viewpoint in the A-seat area (the pre-switch viewpoint), thecommunication delay predicting unit 332 may predict a delay incommunication between the content management server 3 and the userterminal 2 based on the obtained downstream communication speedinformation.

The arrival time predicting unit 333 is configured to predict an arrivaltime at which field-of-view video data that is associated with aswitched-to viewpoint arrives at the user terminal 2, based on thetransmission start time determined by the transmission start timedetermining unit 329 and the communication delay predicted by thecommunication delay predicting unit 332.

A series of processes of the video content distribution system 100Aaccording to at least one embodiment is described next with reference toFIG. 13. The series of processes of the video content distributionsystem according to at least one embodiment in FIG. 13 differs from theseries of processes of the video content distribution system accordingto at least one embodiment in FIG. 8 in the method of determining theS-seat viewing start time (the A-seat viewing start time).

In Step S11, the user terminal 2X first transmits to the contentmanagement server 3 a viewpoint switch request signal for requesting aswitch from a viewpoint in the A-seat area to a viewpoint in the S-seatarea in a field-of-view video that is being displayed on the displayunit 27. Details of Step S11 are the same as details of Step S1, whichis illustrated in FIG. 8. Next, the viewing stop time determining unit326 determines the A-seat viewing stop time (the first viewing stoptime) in Step S12. Details of Step S12 are the same as details of StepS2, which is illustrated in FIG. 8.

In Step S13, the transmission start time determining unit 329 determinesa transmission start time at which the transmission unit 325 startstransmitting field-of-view video data that is associated with theviewpoint in the S-seat area to the user terminal 2X. Details of StepS13 are the same as details of Step S3, which is illustrated in FIG. 8.

In Step S14, the user viewpoint information management table updatingunit 324 updates data in the user viewpoint information management table(see FIG. 9), which is stored in the storage 33. Details of Step S14 arethe same as details of Step S4, which is illustrated in FIG. 8.

In Step S15, the arrival time is predicted based on the communicationdelay and the transmission start time. In at least one embodiment, thecommunication delay predicting unit 332 first predicts a delay incommunication between the content management server 3 and the userterminal 2X. Thereafter, the arrival time predicting unit 333 predictsan arrival time at which the field-of-view video data that is associatedwith the viewpoint in the S-seat area arrives at the user terminal 2X,based on the transmission start time determined by the transmissionstart time determining unit 329 and the communication delay predicted bythe communication delay predicting unit 332. The predicted arrival timeis t3=00:04.

In Step S16, the content management server 3 obtains field-of-view videodata that is associated with the viewpoint in the S-seat area from thecontent server 5S, where 360-degree space video data that is associatedwith the viewpoint in the S-seat area is stored. Details of Step S16 arethe same as details of Step S5, which is illustrated in FIG. 8. In StepS17, the content management server 3 transmits the field-of-view videodata that is associated with the viewpoint in the S-seat area to theuser terminal 2X. Details of Step S17 are the same as details of StepS6, which is illustrated in FIG. 8. Details of Step S18 and Step S19 arethe same as details of Step S7 and Step S8, which are illustrated inFIG. 8.

Next, the viewing start time determining unit 327 determines in Step S20an S-seat viewing start time (the second viewing start time) at whichthe user X starts viewing the field-of-view video from the viewpoint inthe S-seat area, i.e., the post-switch viewpoint. Specifically, theviewing start time determining unit 327 determines as the S-seat viewingstart time the arrival time predicted by the transmission start timedetermining unit 333 (t3=00:04).

According to at least one embodiment, the viewing stop time determiningunit 326 determines as the A-seat viewing stop time an acquisition timeat which a viewpoint switch request signal (in particular, informationcontained in a viewpoint switch request signal, for example, user IDinformation) is obtained (t1=00:02), and an arrival time at whichfield-of-view video data that is associated with the viewpoint in theS-seat area arrives at the user terminal 2X (t3=00:04) is determined asthe S-seat viewing start time. The period between the acquisition timet1 and the arrival time t3 (2 seconds) is not counted as a field-of-viewvideo viewing period in this manner, which helps to improve the user'sdegree of satisfaction with a video content distribution service and toconvince the user more that the charge for the service is fair.

A video content distribution system, e.g. video content distributionsystem 100, according to at least one embodiment of this disclosure isdescribed next with reference to FIG. 14 to FIG. 16. FIG. 14 is adiagram of function blocks of a control unit 22A of the user terminal 2according to at least one embodiment of this disclosure. FIG. 15 is adiagram of function blocks of a control unit 32B of the contentmanagement server 3 according to at least one embodiment. FIG. 16 is asequence diagram of a series of processes of the video contentdistribution system according to at least one embodiment. The videocontent distribution system according to at least one embodiment differsfrom the video content distribution system 100 according to at least oneembodiment in the function of the control unit of each user terminal 2and the function of the control unit of the content management server 3.Specifically, the control unit 22A of each user terminal 2 includes, inaddition to the components of the control unit 22, a time stampgenerating unit 226. A control unit 32B of the content management server3 differs from the control unit 32 in the method that is used by theviewing stop time determining unit 326 to determine a viewing stop timeand the method that is used by the viewing start time determining unit327 to determine a viewing start time.

As illustrated in FIG. 14, the time stamp generating unit 226 isconfigured to generate a first time stamp and a second time stamp byreferring to the current time that is indicated by the time clock 25.The first time stamp indicates a transmission start time at which thetransmission unit 225 starts transmitting a viewpoint switch requestsignal to the content management server 3 (for example, t0=00:01). Thesecond time stamp indicates a display start time at which the displaycontrol unit 223 starts displaying on the display unit 27 thefield-of-view video from the switched-to viewpoint (for example, aviewpoint in the S-seat area) (for example, t3=00:04). The transmissionunit 225 transmits the first and second time stamps generated by thetime stamp generating unit 226 to the content management server 3 viathe communication interface 26.

A series of processes of the video content distribution system accordingto the third embodiment is described next with reference to FIG. 16. Theseries of processes of the video content distribution system accordingto at least one embodiment differs from the series of processes of thevideo content distribution system 100 according to at least oneembodiment in the method of determining the A-seat viewing stop time(the S-seat viewing stop time) and the S-seat viewing start time (theA-seat viewing start time).

In Step S21, the user terminal 2X (transmission unit 225) firsttransmits to the content management server 3 a first time stamp and aviewpoint switch request signal for requesting a switch from a viewpointin the A-seat area to a viewpoint in the S-seat area in a field-of-viewvideo that is being displayed on the display unit 27. The first timestamp is generated by the time stamp generating unit 226, and indicatesa transmission start time at which the transmission unit 225 startstransmitting the viewpoint switch request signal to the contentmanagement server 3 (t0=00:01).

In Step S22, the viewing stop time determining unit 326 determines theA-seat viewing stop time (the first viewing stop time) at which the userX stops viewing the field-of-view video from the viewpoint in the A-seatarea, i.e., the pre-switch viewpoint. In at least one embodiment, theviewing stop time determining unit 326 determines as the A-seat viewingstop time a transmission start time that is indicated by the first timestamp transmitted from the user terminal 2X (t0=00:01). The subsequentsteps from Step S23 to Step S27 are the same as Steps S3 to S7, whichare illustrated in FIG. 8, and descriptions on Steps S23 to S27 aretherefore omitted.

In Step S28, the display control unit 223 displays the field-of-viewvideo from the viewpoint in the S-seat area on the display unit 27,based on the field-of-view video data that is associated with theviewpoint in the S-seat area. The time stamp generating unit 226 thengenerates the second time stamp that indicates a display start time atwhich the display control unit 223 starts displaying on the display unit27 the field-of-view video from the viewpoint in the S-seat area (forexample, t3=00:04). The transmission unit 225 transmits the generatedsecond time stamp to the content management server 3.

In Step S29, the viewing start time determining unit 327 determines theS-seat viewing start time (the second viewing start time) at which theuser X starts viewing the field-of-view video from the viewpoint in theS-seat area, i.e., the post-switch viewpoint. Specifically, the viewingstart time determining unit 327 determines as the S-seat viewing starttime a display start time that is indicated by the second time stamptransmitted from the user terminal 2X (t3=00:04).

According to at least one embodiment, a transmission start timeindicated by the first time stamp at which the transmission unit 225starts transmitting a viewpoint switch request signal to the contentmanagement server 3 (t0=00:01) is determined as the A-seat viewing stoptime, and a display start time indicated by the second time stamp atwhich the display control unit 223 starts displaying on the display unit27 the field-of-view video from the viewpoint in the S-seat area(t3=00:04) is determined as the S-seat viewing start time. The periodbetween the transmission start time t0 and the display star time t3 (3seconds) is not counted as a field-of-view video viewing period in thismanner, which helps to improve the user's degree of satisfaction with avideo content distribution service and to convince the user more thatthe charge for the service is fair.

The above descriptions of some of the embodiments are not to be read asa restrictive interpretation of the technical scope of this disclosure.The above described embodiments are merely given as an example, and aperson skilled in the art would understand that various modificationscan be made to the embodiments within the scope of this disclosure setforth in the scope of patent claims. Thus, the technical scope of thisdisclosure is to be defined based on the scope of this disclosure setforth in the scope of patent claims and an equivalent scope thereof.

What is claimed is:
 1. A video content distribution system comprising: auser terminal on which contents are viewable; and a content managementserver connected to the user terminal via a communication network,wherein the user terminal comprises: a first reception unit configuredto receive field-of-view video data from the content management server;a display control unit configured to generate instructions fordisplaying on a display unit a field-of-view video based on the receivedfield-of-view video data; a viewpoint switch request signal generatingunit configured to generate, in response to input operation on the userterminal, a viewpoint switch request signal for requesting a switch froma first viewpoint to a second viewpoint in the field-of-view videodisplayed on the display unit; and a first transmission unit configuredto transmit the generated viewpoint switch request signal to the contentmanagement server, wherein the content management server comprises: asecond reception unit configured to receive the viewpoint switch requestsignal from the user terminal; a viewing start time determining unitconfigured to determine a first viewing start time at which the displayunit starts displaying the field-of-view video from the first viewpoint,and a second viewing start time at which the display unit startsdisplaying the field-of-view video from the second viewpoint; a viewingstop time determining unit configured to determine a first viewing stoptime at which the display unit stops displaying the field-of-view videofrom the first viewpoint, and a second viewing stop time at which thedisplay unit stops displaying the field-of-view video from the secondviewpoint; a viewing period determining unit configured to determine afirst viewing period in which the field-of-view video is displayed fromthe first viewpoint based on the first viewing start time and the firstviewing stop time, and to determine a second viewing period in which thefield-of-view video is displayed from the second viewpoint based on thesecond viewing start time and the second viewing stop time; a total usercharge amount calculating unit configured to determine a total amount tobe charged to the user based on a combination of charges for a firstviewing duration at the first viewpoint and a second viewing directionat the second viewpoint, wherein a charge per unit time for the firstview point is different form a charge per unit time for the secondviewpoint; and a second transmission unit configured to transmit to theuser terminal field-of-view video data that is associated with one ofthe first viewpoint or the second viewpoint, wherein the contentmanagement server is configured to continue transmitting thefield-of-view video data that is associated with the first viewpoint atleast for a time period from a time when the first transmission unittransmits the viewpoint switch request signal to the second transmissionunit to a time when the first reception unit receives the field-of-viewvideo data that is associated with the second viewpoint from the contentmanagement server, or at least for a time period from a time when thesecond reception unit receives the viewpoint switch request signal to atime when the second transmission unit transmits the field-of-view videodata that is associated with the second viewpoint, and wherein theviewing stop time determining unit and the viewing start timedetermining unit are configured to determine the first viewing stop timeand the second viewing start time, respectively, when the secondreception unit receives the viewpoint switch request signal.
 2. Thevideo content distribution system according to claim 1, wherein thecontent management server further comprises a user charge informationupdating unit configured to update user charge information that isassociated with the first viewpoint based on the first viewing period.3. The video content distribution system according to claim 2, whereinthe user charge information updating unit is further configured toupdate user charge information that is associated with the secondviewpoint based on the second viewing period.
 4. The video contentdistribution system according to claim 1, wherein the total user chargeamount calculating unit is configured to determine the total amount tothe charged to the user based on a viewing duration for eachcorresponding viewpoint of all viewpoints accessed by the user.
 5. Thevideo content distribution system according to claim 1, wherein thecontent management server further comprises a transmission start timedetermining unit configured to determine a transmission start time atwhich the second transmission unit starts transmitting the field-of-viewvideo data that is associated with the second viewpoint to the userterminal.
 6. The video content distribution system according to claim 5,wherein the viewing stop time determining unit is configured todetermine as the first viewing stop time an acquisition time at whichthe viewpoint switch request signal is obtained.
 7. The video contentdistribution system according to claim 5, wherein the viewing start timedetermining unit is configured to determine as the second viewing starttime the transmission start time that is determined by the transmissionstart time determining unit.
 8. The video content distribution systemaccording to claim 1, wherein the content management server furthercomprises: a transmission start time determining unit configured todetermine a transmission start time at which the second transmissionunit starts transmitting the field-of-view video data that is associatedwith the second viewpoint to the user terminal; a communication delaypredicting unit configured to predict a delay in communication betweenthe content management server and the user terminal; and an arrival timepredicting unit configured to predict an arrival time at which thefield-of-view video data that is associated with the second viewpointarrives at the user terminal, based on the determined transmission starttime and the predicted communication delay.
 9. The video contentdistribution system according to claim 8, wherein the viewing stop timedetermining unit is configured to determine as the first viewing stoptime an acquisition time at which the viewpoint switch request signal isobtained.
 10. The video content distribution system according to claim8, wherein the viewing start time determining unit is configured todetermine as the second viewing start time the arrival time that ispredicted by the arrival time predicting unit.
 11. The video contentdistribution system according to claim 1, wherein the user terminalfurther comprises a time stamp generating unit configured to generate afirst time stamp and a second time stamp, the first time stampindicating a transmission start time at which the first transmissionunit starts transmitting the viewpoint switch request signal to thecontent management server, the second time stamp indicating a displaystart time at which the display control unit starts displaying on thedisplay unit the field-of-view video from the second viewpoint.
 12. Thevideo content distribution system according to claim 11, wherein thesecond reception unit is configured to receive the first time stamp andthe second time stamp from the user terminal.
 13. The video contentdistribution system according to claim 11, wherein the viewing stop timedetermining unit is configured to determine as the first viewing stoptime the transmission start time that is indicated by the received firsttime stamp.
 14. The video content distribution system according to claim11, wherein the viewing start time determining unit is configured todetermine as the second viewing start time the display start time thatis indicated by the received second time stamp.
 15. The video contentdistribution system according to claim 2, wherein the total user chargeamount calculating unit is configured to determine the total amount tothe charged to the user based on a viewing duration for eachcorresponding viewpoint of all viewpoints accessed by the user.
 16. Thevideo content distribution system according to claim 2, wherein thecontent management server further comprises a transmission start timedetermining unit configured to determine a transmission start time atwhich the second transmission unit starts transmitting the field-of-viewvideo data that is associated with the second viewpoint to the userterminal, wherein the viewing stop time determining unit is configuredto determine as the first viewing stop time an acquisition time at whichthe viewpoint switch request signal is obtained, and wherein the viewingstart time determining unit is configured to determine as the secondviewing start time the transmission start time that is determined by thetransmission start time determining unit.
 17. The video contentdistribution system according to claim 2, wherein the content managementserver further comprises: a transmission start time determining unitconfigured to determine a transmission start time at which the secondtransmission unit starts transmitting the field-of-view video data thatis associated with the second viewpoint to the user terminal; acommunication delay predicting unit configured to predict a delay incommunication between the content management server and the userterminal; and an arrival time predicting unit configured to predict anarrival time at which the field-of-view video data that is associatedwith the second viewpoint arrives at the user terminal, based on thedetermined transmission start time and the predicted communicationdelay, wherein the viewing stop time determining unit is configured todetermine as the first viewing stop time an acquisition time at whichthe viewpoint switch request signal is obtained, and wherein the viewingstart time determining unit is configured to determine as the secondviewing start time the arrival time that is predicted by the arrivaltime predicting unit.
 18. The video content distribution systemaccording to claim 2, wherein the user terminal further comprises a timestamp generating unit configured to generate a first time stamp and asecond time stamp, the first time stamp indicating a transmission starttime at which the first transmission unit starts transmitting theviewpoint switch request signal to the content management server, thesecond time stamp indicating a display start time at which the displaycontrol unit starts displaying on the display unit the field-of-viewvideo from the second viewpoint, wherein the second reception unit isconfigured to receive the first time stamp and the second time stampfrom the user terminal, wherein the viewing stop time determining unitis configured to determine as the first viewing stop time thetransmission start time that is indicated by the received first timestamp, and wherein the viewing start time determining unit is configuredto determine as the second viewing start time the display start timethat is indicated by the received second time stamp.
 19. The videocontent distribution system according to claim 3, wherein the contentmanagement server further comprises a transmission start timedetermining unit configured to determine a transmission start time atwhich the second transmission unit starts transmitting the field-of-viewvideo data that is associated with the second viewpoint to the userterminal, wherein the viewing stop time determining unit is configuredto determine as the first viewing stop time an acquisition time at whichthe viewpoint switch request signal is obtained, and wherein the viewingstart time determining unit is configured to determine as the secondviewing start time the transmission start time that is determined by thetransmission start time determining unit.
 20. A content managementserver comprising: a reception unit configured to receive a viewpointswitch request signal from a user terminal via a communication network;a viewing start time determining unit configured to determine a firstviewing start time at which viewing display of the user terminal startsdisplaying a field-of-view video from a first viewpoint, and a secondviewing start time at which the display start displaying thefield-of-view video from a second viewpoint; a viewing stop timedetermining unit configured to determine a first viewing stop time atwhich the display stops displaying the field-of-view video from thefirst viewpoint, and a second viewing stop time at which the displaystops displaying the field-of-view video from the second viewpoint; aviewing period determining unit configured to determine a first viewingperiod in which the field-of-view video is displayed from the firstviewpoint based on the first viewing start time and the first viewingstop time, and to determine a second viewing period in which thefield-of-view video is displayed from the second viewpoint based on thesecond viewing start time and the second viewing stop time; a secondtransmission unit configured to transmit to the user terminalfield-of-view video data that is associated with one of the firstviewpoint or the second viewpoint, wherein the field-of-view video datathat is associated with the first viewpoint is continuously transmittedto the user terminal at least for a time period from a time when thesecond reception unit receives the viewpoint switch request signal to atime when the second transmission unit transmits the field-of-view videodata that is associated with the second viewpoint, and wherein theviewing stop time determining unit and the viewing start timedetermining unit are configured to determine the first viewing stop timeand the second viewing start time, respectively, when the secondreception unit receives the viewpoint switch request signal; and a totaluser charge amount calculating unit configured to determine a totalamount to be charged to the user based on a viewing duration at eachviewpoint accessed by the user, wherein the total user charge amountcalculating unit is configured to omit charges incurred during a timeperiod between receipt of the viewpoint switch request signal and thesecond viewing start time.